Rotary pump



Oct- 2, 1962 J. R. PIPER 3,056,356

ROTARY PUMP Filed D60. 18, 1958 Inventor Jack R. Piper 52. MW, fl'flrornegs Patented Oct. 2, 1952 3,tl56,356 ROTARY PUMP Jack R. Piper, Mount Prospect, 11]., assignor to Bell & Gossett Company, a corporation of Illinois Filed Dec. 18, 1958, Ser. No. 781,250 1 Claim. (El. 103-160) This invention relates to positive displacement rotary pumps and particularly to such pumps where the rotor has a diametrically located piston therein that is reciprocated as an incident to rotation of the rotor.

Pumps of the aforesaid character are shown in C. F. Waite Patent No. 2,018,692, patented October 29, 1935, and William J. Sanborn Patent No. 2,655,110, patented October 13, 1953, and as therein shown the reciprocation of the diametric piston within the rotor is attained by means of a stationary eccentric pin engaging a transverse slot in the piston so that in rotation of the rotor, the piston is reciprocated transversely of the rotor in timed relation to the rotation of the rotor, and thus a positive pumping action is produced ta each end of the piston in each rotation of the rotor. Inlet and outlet ports have been provided in the casing at opposite sides thereof for alternate communication with each end of the cylinder in the rotation of the rotor, and in order that such communication may be established throughout the desired portion of the rotative movement of the rotor, it has been the practice heretofore to form recesses within the pump casing that in effect extend the inlet and out let ports for circumferential distances that are related to the cylinder diameter of the pump. Pumps of this type may be of fixed or constant volume, or may be adjustable as to volume as shown in the aforesaid patents.

With prior pumps as thus employed it has been found that these recessed extensions of the inlet and outlet ports have a tendency to come clogged particularly where the pump is being used with viscous materials. Moreover, it has been found that the formation of these recesses within the pump chamber is extremely costly and diificult.

In view of the foregoing it is the primary object of the present invention to enable pumps of the aforesaid type to be made more economically and to be made in such a way as to prevent clogging of the passages within the pump. More specifically it is an object of the present invention to provide a pump of the aforesaid character in which the passages within the pump are so arranged and related that there is a reversal of the direction of flow of material in these passages in each cycle of pump operation, thus to assure that there will be a scouring action to prevent clogging of the passages. Other and related objects of this invention are to pro vide a pump of this character wherein the porting passages are formed circumterentially as grooves in the cylindrical face of the rotor to provide communication between the cylinder and the ports at the proper periods in the rotation of the rotor.

Other and further objects of the present invention will be apparent from the following description and claims, and are illustrated in the accompanying drawings, which, by way of illustration, show preferred embodiments of the present invention and the principles thereof, and what is now considered to be the best mode in which to apply these principles thereof, and what is now considered to be the best mode in which to apply these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the invention.

In the drawings:

FIG. 1 is a longitudinal sectional view taken through a rotary pump embodying the features of the invention;

FIG. 2 is an end elevational view of the pump as viewed from the line 22 of FIG. 1;

FIG. 3 is an enlarged transverse sectional view of the pump taken substantially along the line 33 of FIG. 1 and showing the rotor and the piston in positions that they occupy just prior to the completion of the intake and discharge functions at the opposite ends of the cylinder;

FIG. 4 is a view similar to FIG. 3 and showing the piston in its dead center position wherein reversal of movement is about to be initiated;

FIG. 5 is a view similar to FIGS. 3 and 4 showing the rotor slightly advanced from the position of FIG. 4;

FIG. 6 is a view similar to FIGS. 3 and 5 and showing the rotor in a still further advanced relation;

FIG. 7 is a perspective view of the rotor; and

FIG. 8 is a view similar to FIG. 4 showing the relationship of the ports and passages for use in a reversible pump.

For purposes of disclosure the invention is herein illustrated as embodied in a rotary positive displacement pump 10 having sectional casing 11 within which a generally cylindrical rotor 12 is rotatable within a cylindrical pumping chamber 13, and diametrically aligned suction and discharge ports S and D formed in the casing 11 communicate with opposite sides of the rotor chamber 13 so that a piston 15, mounted for reciprocation diametrically within the rotor 12 in a transverse bore 123 and recoprocated in timed relation to the rotation of the rotor 12, may pump flowable substances from the suction port S and discharge the same through the discharge port D. The timed reciprocation of the piston 15 is attained through cooperation of a pin 16 that is eccentrically located with respect to the axis of the rotation of the rotor 12 and which rides in or engages a transverse slot 17 formed in one side of the piston 15.

The sectional casing 11 comprises a main section 11M and a cap or closure section 11C and the sections are held in their desired endwise relation by a plurality of cap screws 19 and locating pins 20.

The pumping chamber 13 is formed within the main section 11M of the casing 11 by a longitudinal bore extended completely through the section 11M and having a shouldered enlargement 13E formed at its right-hand end, as viewed in FIG. 1, to provide mounting space for sealing and driving means. The enlarged portion is extended somewhat beyond the right-hand face of the section 11M as viewed in FIG. 1, by a sleeve-like extension 1135, and within the enlarged section 13E of the bore, a sealing ring 22 is provided which engages the shoulder at the left-hand end of the enlargement 13E and also engages the outer annular portion of the right-hand end of the rotor 12. A coil spring 23 is mounted in the enlarged bore 13E and is compressed between the sealing ring 22 and an outer fastening ring 24 so that endwise pressure is applied to the sealing ring 22 to urge the same toward the rotor 12. The sealing structure that is thus provided affords center or axial clearance so as to expose the slotted end of a short drive shaft 25 that is threaded into the right-hand end of the rotor 12 axially thereof and through which rotative drive may be transmitted to the rotor 12.

At the other or left hand end of the main casing section 11M, the rotor chamber 13 is closed by the closure section 11C, and preferably, the sealing and closing action is facilitated by a resilient sealing ring 26 that is recessed into the cap section 11C and bears against the left-hand face of the section 11M just outwardly of the adjacent end of the rotor chamber 13.

As above pointed out, the eccentric pin 16 engages the transverse slot 17 in the piston 15, and to enable this to be accomplished, the rotor 12 has a relatively large central bore 28 extending axially into the left-hand end thereof to intersect the bore 12B, and the pin 16 may thus be mounted in the cap section 110 and may extend from the cap section through the bore 28 of the rotor 12 and into engagement with the slot 17 of the piston 15.

It has been pointed out that pumps of the type to which the present invention relates may be made adjustable as to output and this may be accomplished by adjusting means such as that shown in the aforesaid patents, but in the present instance, such adjustability has no patentable relationship to this invention, and hence the pin 16 is shown as being mounted in a fixed position. Thus, the cap section 11C has a bore 31 formed therein in the proper position and relationship, as will be described, and the left-hand end of the pin 16 is mounted in the bore 31. The outer or left-hand end of the bore 31 is closed by a fixed plug 32 and between the plug 32 and the pin 16, a thrust receiving ball 33 is preferably positioned.

The rotor 12 is best shown in FIGS. 3 to 7 of the drawings, and as there shown, it will be apparent that the piston is reciprocably mounted in the transverse bore 1213, the axis of which intersects the axis of the rotor 12, and this transverse bore 128 thus serves to provide what amounts to two aligned cylinders C-1 and C-2 within which the piston 15 may reciprocate. The respective ends of the piston which are located in the cylinders C-1 and G2 are correspondingly identified as ends E1 and E-Z so as to facilitate description of the operation of the pump.

In pumps of this character the structural relationships must be such that the suction and discharge ports S and D are isolated at all times from each other, and another condition that must be met is that the cylinder that has just completely filled during a suction stroke of the piston must be connected to the discharge port D just before or at substantially the time when the discharge stroke of the piston in this filled cylinder is started. Further, the structure must be such that the cylinder that has just been emptied by a discharge stroke of the piston must be connected to the suction port S at or a short time after such suction stroke of the piston starts.

As a preliminary to specific consideration of the factors and relationships that are required for attaining such timed connection of the ports S and D with the cylinders (34 and C2, it is important to note that under the present invention such timing is achieved in part through the use of porting passages P1 and P-Z that are formed as grooves in the cylindrical surfaces of the rotor. The passages P-1 and P-2 are of equal length and are identical in cross sectional size and proportioning, and extend from the respective cylinders C1 and (3-2 circumferentially of the rotor 12 and in the same rotative direction. Each passage P-1 and P-2 terminates short of the other cylinder so as to leave unbroken cylindrical surfaces or lands L on the rotor 12 between the end of the passage 19-2 and the cylinder C-1 and between the end of the passage P1 and the cylinder C2. The passages P-1 and P-Z are formed as generally arcuate grooves that taper from a large end that is connected with the related one of the cylinders to a smaller and shallower end which terminates at the edge of the related land L.

In the present instance, the rotor 12 is intended for rotation in a counterclockwise direction, as indicated by the arrows in FIGS. 3 to 6, and the porting passages P-1 and P2 extend in a counterclockwise or leading direction from the respective cylinders C1 and (1-2 with which they are associated.

The lands L are of equal extent in an arcuate or circumferential direction, as will be evident in FIG. 4 of the drawings, and this arcuate length or extent of the lands L is just slightly less than the circumferential extent or width of the discharge port D. This will also be evident in FIG. 4 of drawings.

The ports 5 and D are of diiferent widths in a circumferential sense, as will be evident particularly in FIG. 4 of the drawings, the suction port S being considerably narrower than the discharge port D. Thus when the rotor 12 is in the position of FIG. 4 with a slight opening or in communication with the cylinder C-1 and with the porting passage P2, the suction port S will be closed and overlapped substantially on both sides by the lower land L so as to fully isolate suction port S from the discharge port D. This isolation is maintained as the rotor continues its motion until a time when the cylinder C-l has been fully isolated from the discharge port D, as will be evident in FIG. 5 of the drawings. The leading end of the passage P-1 then moves into communication with the suction port S so that the cylinder C-1 may be filled in the related suction stroke of the end E1 of the piston 15, while at this same time the material is discharged by the end E-Z of the piston from the cylinder C-Z through the passage P-2 to the port D.

The reciprocation of the piston 15 is timed according to the size and relationship of the cylinders 0-1, C-2, the passages P-1 and P-2, the lands L and the Port D and this timing is dependent upon the location of the eccentric pin 16. Thus when the rotor 12 is in the rotative position in which it is shown in FIG. 4, the porting passage P.2 has just been opened to discharge port D, and hence the rotor 12 is in such a position that the piston 15 should be at one end of its stroke and ready for reversal of movement to discharge material from the cylinder C-2 and to draw material into the cylinder C-l. Thus, in the example mentioned, the piston 15 is located at the end of its discharge stroke with respect to the cylinder C1, and at the end of its suction stroke with respect with cylinder C-2. This may be defined as a dead-center position, and the timed movement of the piston 15 that is required is attained by locating the eccentric pin 16 in a plane 35 that is indicated in FIG. 4 and which is defined by the axis of the rotor and the axis of the piston 15 when the rotor is in the rotative position of FIG. 4. This plane 35 may be termed the plane of eccentricity in the pin 16, and the angle A, FIG. 4, between the plane 35 and the remote or right-hand side of the discharge port D will of course vary according to the diameter of the piston 15, the circumferential width of the discharge port D and the arcuate extent of the lands L. Fundamentally, however, the location of the plane of eccentricity is so determined that the piston 15 will be at the proper end of its reciprocating stroke when the porting passage P-2 of the filled cylinder first enters into communication with the discharge port D.

Through the use of the porting passages P-1 and P-2 formed as grooves in the external cylindrical surface of the rotor 12, the manufacture of the pump has been greatly simplified, since the passages P-1 and P-2 may be formed by simple milling operations on exposed and readily accessible surfaces of the rotor.

The passages P-1 and P2 of course cooperate with the cylinders C1 and C2 and the ports S and D to attain the desired timing of the pump, and the functioning of the passages P-1 and P-2 in attaining this result is such that all tendency toward clogging of the pump is eliminated. I attribute this improved pump operation to alternate reversals of flow of materials in each of the passages P-1 and P-2 in each rotation of the rotor. Thus, in FIG. 4 of the drawings, where the discharge of the material from the cylinder C-2 is about to start, the flow of the material through the passage P2 will be in a leading direction, or in other words, in a counterclockwise direction. Then, after a substantial period of such forward flow of material in the passage P2, there will be a period just prior to the end of the discharge stroke when there will be no appreciable flow in the leading portion of the passage P-2. As the pumping operation continues, however, the leading end of the passage P-2 will move into communication with the suction port S, and when this takes place, the flow of material through the passage P2 from the suction port S will be in a trailing or clockwise direction which, of course, is the reverse of the direction of the material flow that has taken place in the discharge functioning of this passage. As a result, there is an effectual scouring of the passage by reversals of flow of material therein, and even though the material being pumped may have a tendency to harden over a period of time, such material may nevertheless be successfully pumped or metered because the material does not have an opportunity to remain at rest for any appreciable length of time.

The embodiment of the invention illustrated in FIGS. 1 to 7 is adapted and constructed for pumping only in one direction through the system, but it is known as set forth in the aforesaid Sanborn patent, that pumps of this general type are in some instances constructed for reversible operation so that the direction of flow in the system may be reversed. Such reversal is attained by shifting the operating pin, such as the pin 16, along its plane of eccentricity, such as the plane 35 from one side of the rotor axis to the other side, as taught in the aforesaid Sanborn patent.

The new and advantageous porting system of the present invention is also applicable to reversible pumps of this type, as illustrated in FIG. 8 where a pump casing 111 has a rotor chamber 113 with a rotor 112 therein, and a diametric bore 112C in the rotor is adapted to re ceive a pumping piston. ports DD and SS opening radially into the chamber 113, and in order to attain reversibility these ports have the same diameter or dimension circumferentially of the chamber 113.

The rotor 112 has circumferential porting passages PP1 and PP-2 formed in the manner hereinbefore described and extending in the same circumferential direction from the opposite ends of the cylinder 112C. The

porting passages PP-l and PP2 are of equal length so that lands LL of equal length are provided, and these lands LL must have a circumferential dimension at least equal to but not appreciably exceeding the circumferential dimension of the ports DD and SS. This arrangement and proportioning avoids objectionable hydraulic lock and enables the advantageous porting passages of this invention to be employed in a reversible pump.

From the foregoing description it will be apparent that the present invention provides an improved positive displacement pump, and that this pump is of such a character The casing 111 has diametric t that the passages within the pump are protected against clogging of material therein.

It will also be apparent that the present invention enables positive displacement pumps of this type to be manufactured more economically than heretofore.

Thus while I have illustrated and described a preferred embodiment of my invention it is to be understood that changes and variations may be made by those skilled in the art without departing from the spirit and scope of the appending claim.

I claim:

In a positive displacement rotary pump for handling high viscosity flowable material, a casing having a cylindrical chamber therein and inlet and outlet ports opening radially into said chamber at opposite sides of the chamber, a cylindrical rotor having a cylindrical surface and rotatable in said chamber and having a diametric bore therein defining aligned cylinders opening through said cylindrical surface on opposite sides of the rotor, a piston reciprocable in said bore for pumping cooperation of its opposite ends with the respective cylinders, means acting between said casing and said piston and operable as an incident to rotation of the rotor for reciprocating the piston through a complete forward and return movement in each such rotation, and a pair of porting passages formed as circumferentially extending grooves in the cylindrical surface of the rotor and extending respectively from points of juncture with opposite ends of said bore in the same circumferential direction and each terminating short of the respective other ends of the bore, said porting passages being of equal length and decreasing gradually in cross sectional area and depth throughout their entire lengths from a larger cross sectional area at their points of juncture with the bore to an extremely small cross sectional area at their other ends.

References Cited in the file of this patent UNITED STATES PATENTS 1,278,125 Englund Sept. 10, 1918 1,315,141 McVoy Sept. 2, 1919 1,370,317 Janssen Mar. 1, 1921 1,988,407 Zierden Jan. 15, 1935 2,079,119 Hillis May 4, 1937 2,633,104 Lauck, et a1. Mar. 31, 1953 2,655,110 Sanborn 'Oct. 13, 1953 FOREIGN PATENTS 532,658 Germany Sept. 3, 1931 

